An embodiment of the invention relates generally to frames that support glazings for windows, and more specifically, to an improved primary frame for supporting security glazings, e.g. glazings that are designed to mitigate explosive blasts. Other embodiments are also described and claimed.
In an increasingly violent society, businesses and government institutions are subject to a greater number of threats against both life and property. Such threats may be in the form of ballistic threats, explosive blasts, forced entries, as well as others. Security measures have been taken to protect against such threats. These include the installation of special windows that have increased strength, to withstand an attack. For example, windows that have security glazings that can resist certain explosive blasts, ballistic threats, and/or forced entry threats are being specified in new commercial, as well as industrial buildings. Such windows may also present better resistance to natural disasters such as hurricanes, tornadoes, and severe storms.
Conventional windows that call for security glazings have a primary frame to secure a glazing unit, within a defined casement opening of a building, for example. The frame is referred to as a “primary” frame because it may be the only frame that is needed to close the given opening between a “threat side” and a “safe side”. Where the threat side is outside of the building, and the safe side is inside the building, the primary frame serves not only to secure the glazing, but to also weatherproof the opening. A conventional method for installing a primary, ballistic resistant glazing frame involves pre-welding four L-shaped pieces of solid steel that are sized to fit a given opening of the building and then bringing the welded sub-frame to the job site, anchoring this welded sub-frame to the building material that surrounds the opening (such as a sill, king studs, and a header), placing the glazing unit against the secured sub-frame, and then anchoring four pieces of square, tubular steel glazing stop to all four sides of the sub-frame to secure the glazing in place.